1. Field of the Invention
The present invention relates to a compressor, and more particularly, to a compressor capable of enhancing a capability and a reliability by preventing an eccentric motion of a piston.
2. Description of the Conventional Art
Generally, a compressor is an apparatus for sucking, compressing, and discharging gas while a piston is reciprocated in a cylinder.
As shown in FIG. 1, the conventional compressor comprises: a casing 10 to which a suction pipe 12 for sucking gas and a discharge pipe 14 for discharging compressed gas are respectively connected; a reciprocating motor 30 disposed in the casing 10, for generating a driving force; a compressing unit 40 for sucking, compressing, and discharging gas by a driving force of the reciprocating motor 30; a resonant spring unit 50 for inducing a resonance motion to a reciprocating motion of the reciprocating motor 30; and a frame unit 20 for respectively supporting the reciprocating motor 30, the compressing unit 40 and the resonant spring unit 50.
The reciprocating motor 30 includes: an outer stator 31; an inner stator 32 disposed to maintain a certain air gap with an inner circumference of the outer stator 31; a magnet 34 disposed between the outer stator 31 and the inner stator 32; and a magnet holder 33 connected to the magnet 34 and reciprocated by an electromagnetic interaction between the outer/inner stators 31/32 and the magnet 34.
The compressing unit 40 includes: a cylinder 41 having an inner space therein; a piston 42 disposed in the cylinder 41, having a gas suction path F therein, and reciprocated by being connected to the magnet holder 33 of the reciprocating motor 30, for varying a volume of a compressing space P inside the cylinder 41; a suction valve 43 mounted at a front side of the piston 42 and operated by a pressure inside the compressing space P, for opening and closing a gas inlet; a discharge valve 44 installed at a front side of the cylinder 41 for opening and closing a gas outlet; a valve spring 45 for elastically supporting the discharge valve 44; and a discharge cover 46 communicated to the discharge pipe 14 through a guiding pipe 16 and accommodating the discharge valve 44 and the valve spring 45.
The frame unit 20 includes: a first frame 21 mounted at a front side of the reciprocating motor 30 and the cylinder 41; a second frame 22 connected to the first frame 21, for supporting the reciprocating motor 30 with the first frame 21; and a third frame 23 connected to the second frame 22, for supporting the resonant spring unit 50 with the second frame 22.
The resonant spring unit 50 includes: a spring seat 53 disposed between the second frame 22 and the third frame 23 and reciprocated by being connected to the piston 42; a first resonant spring 51 disposed between the second frame 22 and the spring seat 53, and shrunk when the piston 42 forwardly moves and extended when the piston 42 backwardly moves; and a second resonant spring 52 disposed between the third frame 23 and the spring seat 53, and extended when the piston 42 forwardly moves and shrunk when the piston 42 backwardly moves.
As shown in FIG. 2, the second frame 22 is formed as a disc shape, and is provided with a spring fixing protrusion 22a to which the first resonant spring 51 is fixed. The third frame 23 is formed as a curved plate shape so that a space for accommodating the spring seat 53 is provided, and is provided with a spring fixing protrusion 23a for fixing the second resonant spring 52. Also, a flange portion 23b having a predetermined width L is formed at both ends of the third frame 23b. The flange portion 23b is coupled to the second frame 22 by a bolt B or a welding method, thereby fixing the third frame 23 to the second frame 22.
The spring seat 53 includes: a connection portion 70 formed as a disc shape and connected to one end of the magnet holder 33 or the piston 42; a pair of first supporting portions 80 respectively and radially extended from the connection portion 70 to have a phase difference of 180° each other, and respectively provided with a first protrusion 82 for fixing the first resonant spring 51; and a pair of second supporting portion 90 respectively and radially extended from the connection portion 70 to have a phase difference of 90° with the first supporting portions 80, and respectively provided with a second protrusion 92 for fixing the second resonant spring 52.
The first resonant spring 51 is respectively fixed to the spring fixing protrusion 22a of the second frame 22 and the first protrusion 82 of the first supporting portion 80 of the spring seat 53, and the second resonant spring 52 is respectively fixed to the resonant spring fixing protrusion 23a of the third frame 23 and the second protrusion 92 of the second supporting portion 90 of the spring seat 53.
As shown in FIG. 3, a distance d1 from the center of the spring seat 53 to the center of the first protrusion 82 of the first supporting portion 80 is greater than a distance d2 from the center of the spring seat 53 to the center of the second protrusion 92 of the second supporting portion 90. That is, the radius d1 of a circle connecting each center of a pair of the first resonant springs 51 is greater than the radius d2 of a circle connecting each center of a pair of the second resonant springs 52.
According to this, loads of the first and second resonant springs 51 and 52 applied to the spring seat 53 are not uniformly applied to a circumferential direction of the spring seat 53, but are eccentrically applied. By these eccentric loads, the spring seat 53 performs an undesired rotational motion at the time of a linear reciprocation thereof. According to this, the piston 42 connected to the spring seat 53 and the magnet holder 33 performs unstable motions, a vibration is generated, and an abrasion due to a friction between the piston 42 and the cylinder 41 may occur, thereby lowering a capability of the compressor.